Source

Purpose

This report summarizes the latest research (since 2000) on the benefits of green space, focussing on “turfgrass” or “turf” - typically associated with the broader notion of “green space,”
which typically connotes such turf-related surfaces as residential lawns, commercial or
institutional turf surfaces and public facilities such as parks and playing fields.

The data for each section of the Report, e.g. Erosion
control, were compiled and reviewed to ensure that they met the following criteria:
• Impartial, objective and balanced review of data.
• An adequately comprehensive review of data.
• Proper used of “weight of evidence” in evaluating data.
• Clear linkage between the data cited and the conclusions made in the study.
• Use of independent scientific peer review to assure study quality
• Studies since 2000.

Evidence

Erosion Control and Run-off Prevention Findings (p7):
1. One of the most significant functions of green space is to stabilize and protect
the soil against water and wind erosion.
2. The New York City sewage treatment system could save billions in operating
costs over time if more rainwater was absorbed naturally through the City’s
52,236 acres of yards as most of the 27 billion gallons of water flow is clean
rainwater.
3. Healthy, dense green space is three times more effective than weedy,
unhealthy green space in preventing nitrogen run-off.
4. When compared to a non-green space areas (like a garden or agricultural
field), green space areas can reduce runoff-induced soil erosion by up to 600
times.

Water Purification Findings (p10):
1. Not only do green spaces absorb rainfall, but they also trap and remove
pollutants, which are broken down by the root system and soil microbes.

Air Purification Findings (p11):
1. Well maintained green space purifies and traps more than 12 million tons of
dust, soil and other particulate matter annually, protecting human health and the
environment.
2. Maintenance of green space in urban areas is especially important for air
purification, because urban areas contain the most particulate matter, due to
abundance of motorized vehicles, and because of the high incidence of asthma and
other breathing disorders in inner city urban areas.

Temperature Modification/Energy and Cost Savings Findings (p13):
1. Green spaces not only can moderate temperature increases in suburban areas
but also is becoming increasingly recognized as important in urban areas, not only
now but in planning for the future.
2. Trees, shrubs and lawn areas around homes can reduce air temperatures from 7°
to 14° F. through the effects of shading and the cooling effect of the transpiration
and evaporation of water through plant leaves. This can directly result in curbing
summer air conditioning costs.
3. One estimate suggests that strategic planting of lawns and other landscape plants
could reduce total U.S. air conditioning energy requirements by 25 percent,
potentially saving 64.5 billion kilowatt hours of energy (approximately 30 million
tons of coal) and $6.3 billion.
4. Manhattan is on average seven degrees hotter than surrounding suburban areas.
The heat-island effect, as its known, could be reduced during the summer if enough
paved yards were replaced with green spaces.
5. The use of urban green space offers significant potential in moderating the
increase in summer temperatures expected with climate change. Modeling data
(Manchester, U.K.) indicate that adding 10 per cent green space in high-density
residential areas and town centers kept maximum surface temperatures at or below
1961–1990 baseline levels up to the 2080s. Conversely, if green space in high-density
residential areas and town centers is reduced by 10 per cent, surface temperatures
will be 7°C [12.6°F] or 8.2°C [14.8°F] warmer by the 2080s. These results indicate
that, despite the projected effects of climate change, addition of 10% green space in
high density urban areas will allow cities to maintain current summer temperature
levels (and thus current summer utility costs) for the next 70 years.

Oxygen Generation Findings (p16):
1. Green spaces absorb carbon dioxide and water and use sunlight during
photosynthesis to produce organic compounds for growth and release oxygen to the
environment.
2. The amount of oxygen produced by green spaces is phenomenal – a 50 by 50 foot
lawn release enough oxygen for a family of four, an average 18-hole golf course
release enough oxygen for 4000 to 7000 people and the grass and trees along the U.S.
interstate highway system releases enough oxygen for 22 million people.

Carbon Sequestration Findings (p18):
1. Urban green spaces provide an important sink to offset carbon emission in the
USA while also adding to the amounts of carbon sequestration annual in U.S.
cropland, grazing land and forest soils.
2. Focusing on soils alone, carbon sequestration within urban green spaces in the
USA is estimated to sequester 12 to 15 million tons of carbon per year, an amount
comparable to the US Department of Agriculture’s Conservation Reserve Program
and equivalent to 14% of the privately owned, cultivated cropland in the USA.
3. While the evidence clearly suggests that properly maintained green space is a net
benefit in the effort to sequester carbon from the atmosphere, further study is
required to determine precisely how significant the net carbon sequestration benefit
is to the environment vis-à-vis such offsetting factors as fuel expense in maintaining
green spaces, fertilizer and pesticide use, energy for water costs, etc.

HUMAN HEALTH Recreation/Increased Physical Activity/Reduced Obesity Findings (p21):
1. Green spaces provide an ideal surface for a variety of recreational and sports
activity, including high use areas such as public parks and playgrounds, sports
fields, etc.
2. Considerable evidence is now developing from studies in the U.S., Europe and
Japan that access to green space is an important predictor of a higher level of
physical activity (called “active living”), reduced risk of obesity and longer life
(reduced mortality from cardiovascular disease and reduced overall mortality).
3. A recent study of over 40 million people in England shows that health
disparities between high income and low income people are much narrow in
areas with ample green space, possibly because it allows residents to become
more physically active and reduce stress.

Healthcare/Reduced Stress Findings (p24):
1. Medical studies have demonstrated that being in, or viewing a green space for
a fairly short period of time, just a few minutes, reduces stress. This has been
demonstrated not only for hospital patients but also for the general public